Polycrystal-state silicon, that is, polysilicon or polycrystalline silicon is a component used as a basic material in solar energy generation industry and semiconductor industry, and recently, the demand thereof has been rapidly increased with the development of the corresponding industries.
In the manufacturing method of polysilicon, a silicon precipitation process (alternatively, a chemical vapor deposition process) of forming polysilicon in a solid state from silane source gas is representative.
The silicon precipitation process generates silicon particles through a hydrogen reduction reaction and pyrolysis of the silane source gas at a high temperature and the silicon particles are formed in a polycrystalline state on the surface of rods or particles to be precipitated.
As an example, a simens precipitation method using a chemical vapor deposition reactor, a precipitation method using a fluidized bed reactor, and the like are included.
The simens chemical vapor deposition reactor is a batch process apparatus as a polysilicon manufacturing process.
In the chemical vapor deposition method, a silicon filament (Si filament) having a diameter of 7 to 10 mm and a length of 2,500 to 3,000 mm in the reactor is installed, resistor heating is generated by applying power to the Si filament, and source gas is injected for 60 to 80 hours under a high-pressure condition to produce silicon rod (Si rod) having a diameter of 120 to 150 mm.
For example, during the chemical vapor deposition process, the source gas is introduced from the lower portion of the reactor and then is discharged to the lower portion again by shifting a direction at the upper portion to form a turbulent flow.
The turbulent flow increases heat loss by convection to increase an electric basic unit.
By the turbulent flow, when the source gas is left between the introducing flow and the discharging flow, hot spots are formed to increase a deviation in gas velocity around the silicon rod, a deviation in diameter of the Si rod, and a deviation in surface temperature of the Si rod.
When the surface temperatures of the Si rods are nonuniform, a popcorn is generated around the hot spot to deteriorate productivity and quality of the polysilicon. That is, competitiveness of the polysilicon is lowered.